Method for debonding of orthodontic metal brackets with eugenol emulgel

ABSTRACT

The invention is directed to a composition that safely removes a cured dental cement or resin from metal brackets, metal braces, and enamel surfaces of teeth. It contains eugenol, isoeugenol, methyl-eugenol or an isomer thereof. A method for removing orthodontic fixtures adhered with a dental cement or resin to the enamel surfaces of teeth from these surfaces by contacting the dental cement or resin with a composition containing eugenol.

BACKGROUND Field of the Invention

A method for removing a dental bracket, appliance, or prosthetic boundto a tooth or teeth with a dental adhesive or cement by contacting thedental adhesive or cement with an eugenol emulgel or eugenol in gelform. This method may be used to remove dental orthodontic brackets,fixed orthodontic appliances, fixed prosthetic elements, such ascemented laminates, veneers, fixed dental crowns, and fixed dentalbridges bound to a tooth or to teeth.

Description of Related Art

The “background” description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventor(s), to the extent it is described in thisbackground section, as well as aspects of the description which may nototherwise qualify as prior art at the time of filing, are neitherexpressly or impliedly admitted as prior art against the presentinvention.

Orthodontic fixed appliance treatment is a comprehensive procedure thatstarts with bonding brackets onto enamel surfaces of teeth and that endswith debonding of the brackets and removal of the brackets and residualbonding material from the enamel surfaces. Removal of the brackets isnot difficult, but care must be taken during treatment with brackets toavoid breakage of the dental appliance containing the brackets anddamage to tooth enamel. Brackets bonded directly to the teeth areremoved by slightly deforming the base of the bracket. When the base ofthe bracket is squeezed, the bond releases and the bracket will comeoff. Usually, the separation occurs at the bracket-glue junction,leaving adhesive on the tooth surface. The orthodontist must then goback and remove the adhesive from each tooth. The process of removingbrackets and the bonding cement or adhesive is relatively painless.After the braces have been removed, adhesive remaining on the teeth mustbe removed. This is usually done with a slow or high-speed dental handpiece that is the same type of instrument used by general dentists whenthey repair a cavity.

During debonding a dental practitioner will aim to limit this removal tothe adhesive only leaving the enamel in its normal condition. However,conventional debonding procedures are risky as they can crack, flake, orfracture the enamel surface of a tooth as described by Pont H B, OzcanM, Bagis B, Ren Y. “Loss of surface enamel after bracket debonding: anin-vivo and ex-vivo evaluation”. Am J Orthod Dentofacial Orthop 2010;138:387 e1-389; and by Dumbryte 1, Linkeviciene L, Malinauskas M,Linkevicius T, Peciuliene V, Tikuisis K. “Evaluation of enamelmicro-cracks characteristics after removal of metal brackets in adultpatients”. Eur J Orthod 2011; 35:317-322, each incorporated herein byreference in its entirety.

Another significant risk is a ceramic bracket fracture when conventionaldebonding procedures are used to debond ceramic brackets as described byTheodorakopoulou L P, Sadowsky P L, Jacobson A, Lacefield W. “Evaluationof the debonding characteristics of 2 ceramic brackets: an in vitrostudy”. Am J Orthod Dentofacial Orthop 2004; 125:329-336; and byFernandes T M F, Janson G, Somensi J, Pinzan A, Francisconi P A S,Sathler R, “Effects of modifying the bonding protocol on the shear bondstrength of metallic and ceramic orthodontic brackets”. Gen Dent 2012; 60:51-55, each incorporated herein by reference in its entirety.

Many prior attempts have been made to solve these problems by reducingdebonding forces to safely remove a dental appliance intact and toprevent damage to tooth enamel. However, while some of these attemptsproved to be effective in reducing the debonding force, they resulted infurther complications including pulpal damage caused by electrothermaldevices or increases in adhesive remnants after treatment with laserdevices as described by Jost-Brinkmann P-G, Radlanski R J, Ãrtun J,Loidl H. “Risk of pulp damage due to temperature increase duringthermodebonding of ceramic brackets”. Eur J Orthod 1997; 19:623-628;lijima M, Yasuda Y, Muguruma T, Mizoguchi 1. “Effects of CO₂ laserdebonding of a ceramic bracket on the mechanical properties of enamel”.Angle Orthod 2010; 80:1029-1035; and by Ahrari F, Heravi F, Fekrazad R,Farzanegan F, Nakhaei S. “Does ultra-pulse CO₂ laser reduce the risk ofenamel damage during debonding of ceramic brackets?” Lasers Med Sci2012; 27:567-574, each incorporated herein by reference in its entirety.

Orthodontic practitioners face a dilemma of using bonding proceduresthat produce strong and durable bonds that withstand forces appliedduring orthodontic treatment but which are difficult or unsafe toremove; and using less effective bonding procedures that are more easilydebonded. Resolving this dilemma presents many challenges.

Composite resins are used in dentistry and orthodontia as bondingmaterials suitable for bonding to dental substrates, such as dentin,enamel, metal, ceramic, porcelain, and zirconia. They are used to bondorthodontic brackets to surfaces of teeth as well as to bond dentalrestorative materials such as glass ceramics, metal, composite resin,and zirconium oxide to teeth or other dental surfaces.

A dental composite resin may be a material that is light-cured,self-cured, and dual-cured. Generally a composite resin will contain apolymerizable monomer, a filler, and a polymerization initiator (e.g., achemical catalyst or light). Composite resins are most widely used todayas restorative materials for repairing fractures of teeth and dentalcaries or for orthodontic bonding. A cured composite resin is obtainedafter polymerization or curing of its ingredients and generally willhave sufficient mechanical strength and hardness to serve as asubstitute for natural teeth, provide wear resistance against occlusionof teeth in an oral cavity, have a surface smoothness and gloss, providecolor matching with natural teeth, and provide translucency ortransparency.

As a composite resin forming paste which has not yet been polymerizedand cured, the composite resin should provide for ease of handling bydental or orthodontic clinicians and technicians, for example, it shouldexhibit proper fluidity and forming properties, adhere to surfaces to bebonded, but have substantially no adhesion to instruments used to applyit.

The micro-hardness and surface roughness of composite resins have beenreported to be significantly affected by some chemical agents includingtopical fluoride agents (e.g., by Second Taste Gel which contains sodiumfluoride), by coffee, and by low pH beverages as described by Yeh S-T,Wang H-T, Liao H-Y, Su S-L, Chang C-C, Kao H-C, et al., “The roughness,microhardness, and surface analysis of nanocomposites after applicationof topical fluoride gels”. Dent Mater 2011; 27:187-196; by Silva Jr J,Resin C, Microscope A F. “Analysis of Roughness and Surface Hardness ofa Dental Composite using Atomic Force Microscopy and MicrohardnessTesting. Microsc Microanal”, 2011; 17:446-451; and by Hamouda I. M.,“Effects of various beverages on hardness, roughness, and solubility ofesthetic restorative materials”. J Esthet Restor Dent 2011; 23:315-322,each incorporated herein by reference in its entirety.

Limited studies have investigated the use of chemicals as debondingagents in orthodontic therapy. Larmour et al., in (1998), studied theeffect of a marketed debonding agent that was based on peppermint oil(P-de-A®, Oradent, U.K.) on the debonding behavior of ceramic bracketsand compared it to two well recognized softening agents; acetone andethanol as described by Larmour C J, McCabe J F, Gordon P H. “An ex vivoinvestigation into the effects of chemical solvents on the debondbehavior of ceramic orthodontic brackets”. Br J Orthod 1998; 25:35-40,incorporated herein by reference in its entirety. After application ofpeppermint oil for an hour, a decrease in the debonding strength and inthe amount of adhesive remaining after debonding was reported. However,peppermint oil was not sufficient to significantly reduce the risk ofceramic bracket fracture.

In contrast to peppermint oil, eugenol is a phenylpropene, an allylchain-substituted guaiacol and a member of the phenylpropanoids class ofchemical compounds. It is a colorless to pale yellow, aromatic oilyliquid extracted from certain essential oils especially from clove oil,nutmeg, cinnamon, basil and bay leaf. It is present in concentrations of80-90% in clove bud oil and at 82-88% in clove leaf oil. The chemicalstructure of eugenol is shown below:

Eugenol is a phenol derivative that is used in combination with zincoxide (ZnO) as a pulp capping agent, temporary cement and root canalfilling cement. Eugenol-containing materials have several advantages asbases for restorations and eugenol is claimed to have sedative,anti-inflammatory, and analgesic effects on dental tissues as describedby Hashimoto S, Maeda M, Yamakita J, Nakamura Y. “Effects of zincoxide-eugenol on leucocyte number and lipoxygenase products inartificially inflamed rat dental pulp”. Arch Oral Biol 1990; 35:87-93;by Lee Y-Y, Hung S-L, Pai S-F, Lee Y-H, Yang S-F. “Eugenol suppressedthe expression of lipopolysaccharide-induced proinflammatory mediatorsin human macrophages”. J Ended 2007; 33:698-702; by Li H Y, Lee B K, KimJ S, Jung S J, Oh S B. “Eugenol inhibits ATP-induced P2X currents intrigeminal ganglion neurons”. Korean J Physiol Pharmacol 2008;12:315-321; and by Boeckh C, Schumacher E, Podbielski A, Haller B.“Antibacterial activity of restorative dental biomaterials in vitro”.Caries Res 2001; 36:101-107, each incorporated herein by reference inits entirety. Eugenol has been reported to stimulate theremineralization of carious dentin. Zinc oxide eugenol (“ZOE”, which areoften used as temporary fillings, is considered a better thermalinsulator than most other lining materials as described by Little P A G,Wood D J, Bubb N L, Maskill S A, Mair L H, Youngson C C. “Thermalconductivity through various restorative lining materials”. J Dent 2005;33:585-591, incorporated herein by reference in its entirety.

Eugenol is a chemical agent found in multiple dental materials includingdental cements, filling materials, impression materials, endodonticsealers, periodontal dressing materials, dry socket dressings, ananalgesics. Potnis, et al., U.S. Pat. No. 9,463,159 describes an oralgel containing eugenol, cooling agents, and camphor for relief of toothpain. Prior compositions containing eugenol were used for pulp relief,usually applied after drilling a tooth cavity, and used as a temporaryfilling that set when it came into contact with saliva. Sometimes suchcompositions were used as temporary fillings for caries prior to removalof the caries. The contemporary use of eugenol for such purposes is nowextremely rare because doctors commonly prescribe oral analgesics torelief pulpal pain and inflammation and because contemporary cappingmaterials can be directly contacted with pulp to induce healing andreparative action in pulp cells. Thus, eugenol is not commonly used inmodern dentistry.

The concentration of eugenol used in such materials is consideredbiologically inert, as there are only rare cases with adverse effectsreported in the literature from its intra-oral application as describedby Deshpande A, Verma S, Macwan C. “Allergic Reaction Associated withthe use of Eugenol Containing Dental Cement in a Young Child”. Austin JDent 2014; 1:1007, incorporated herein by reference in its entirety.

Studies of the effects of eugenol on the bond strength of resin bondinghave produced contradictory findings. Although it has been claimed thateugenol-containing temporary cements compromise the resin-dentin bondstrength of the permanent resin based cements, the overall effects werecontroversial and technique sensitive as described by Carvalho C N,Loguercio A D, Reis A. “Effect of ZOE Temporary Restoration onResin-Dentin Bond Strength Using Different Adhesive Strategies”. JEsthet Restor Dent 2007; 19:144-152, incorporated herein by reference inits entirety.

Eugenol has shown to have an effect on composite resins and previousstudies showed that the bond strength of both types of compositeadhesives (etch-and-rinse or self-etch) was significantly affected after24 h of contact with ZOE as described by Pinto K T, Stanislawczuk R,Loguercio A D, Grande R H M, Bauer J. “Effect of exposure time of zincoxide eugenol restoration on microtensile bond strength of adhesives todentin”. Rev Port Estomatol Med Dent Cir Maxilofac 2014; 55:83-88; andNasreen F, Guptha A B S, Srinivasan R, Chandrappa M M, Bhandary S,Junjanna P. “An in vitro evaluation of effect of eugenol exposure timeon the shear bond strength of two-step and one-step self-etchingadhesives to dentin”. J Conserv Dent 2014; 17:280-284, each incorporatedherein by reference in its entirety. However, bond strength wasre-established and became similar to their control groups after 7 days.These latter studies clarified that eugenol effects on compositerestorations were temporary and limited to small areas.

Some attempts have been reported in the literature assessing the effectof eugenol and other solvents on the debonding behavior of orthodonticbrackets. He, et al. reported that eugenol in IRM (IntermediateRestorative Materials) reduced the mechanical properties of compositeresin within a limited range that does not affect the functionality ofthe restoration as described by He L-H, Purton D G, Swain M V. “Asuitable base material for composite resin restorations: Zinc oxideeugenol”. J Dent 2010; 38:290-295, incorporated herein by reference inits entirety. However, the effects of eugenol on functional propertiesand debonding of composite resins is still under debate.

In view of the dilemma faced by orthodontic practitioners of providing abonding resin or cement that is strong and durable, but which can beeasily removed without substantial damage to enamel surfaces of teeth,the inventors investigated use of eugenol as a safe debonding agent. Asshown herein, the inventors prepared eugenol in a gel form or as an“emulgel” that exhibited a surprising ability to reduce microhardness oforthodontic adhesive bonding resins and that facilitated the saferemoval of orthodontic metal brackets as well as the removal of residualbonding resin for enamel surfaces of teeth.

BRIEF SUMMARY OF THE INVENTION

The invention is directed to a safe, non-toxic composition (e.g.,emulgel) comprising eugenol or a derivative of eugenol in a gel or otherviscous form suitable for application and adhesion to cured or hardeneddental cement or bonding resins in the mouth. Once applied to a dentalcement or resin, the composition reduces microhardness and permits itsremoval without substantial damage to the enamel surfaces of teeth or tothe dental apparatus that is removed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B. FIG. 1A shows the design of the AEZ debonding pliermounted on the Instron machine, and FIG. 1B shows how the distances (a)and (b) used to calculate the actual debonding force are measured.

FIGS. 2A, 2B and 2C depict debonding equipment. A model fororthodontically treated patient ready for debonding is shown by FIG. 2A.A flexible tray constructed on the model allowing space for the emulgelapplication and sealing off the effect of emulgel from the gingiva isshown by FIG. 2B. The flexible tray filled with the emulgel and ready tobe used intraorally is shown by FIG. 2C. Trays and eugenol-containingemulgel may be distributed to orthodontic subjects prior to debondingprocedures, for example, for use 4, 6, 8, 10, 12, 16, 20 or 24 hoursbefore a procedure.

FIG. 3 shows the mean and standard deviations of the Vickersmicrohardness values for the two groups assessed. Error bars indicate astandard deviation. A significant difference was found at p<0.05.

FIG. 4 depicts Table 1. This table shows descriptive statistics for theshear debonding force (MPa) for three assessed groups. Using One-wayANOVA & Post Hoc Tukey's test; means with different letters indicates asignificant difference at p<0.05.

FIG. 5 depicts Table 2. This table which describes the number andpercentages of teeth under each ARI category for all the groups. UsingKruskal Wallis test, no significant difference was found at p<0.05.However, in combination with other data herein, these results show thatat least similar amounts of bonding material were removed by debondingwith a eugenol-containing emulgel according to the invention whilerendering debonding safer due to decreases in Vickers hardness of dentalcement or resin and debonding forces.

DETAILED DESCRIPTION OF THE INVENTION

As disclosed herein the inventors sought to improve the efficacy andsafety of dental debonding procedures, such as those involving removalof metal brackets bound via a dental cement or dental resin to theenamel surfaces of teeth. Eugenol is conventionally used to maketemporary dental cements, for example, in combination with zinc oxideand is also a component of clove oil. Thus, it is recognized as safeboth as a food ingredient and in dental materials. However, eugenol is aliquid and quickly dissipates when placed in the mouth. Moreover, itscapacity to reduce the hardness of cured dental cements and resins aswell as to facilitate the removal of dental brackets from teeth had notbeen established. The inventors disclose herein a method for reducingthe hardness of cured dental cements and resins and for more safelyremoving dental brackets and other dental appliances or prosthetics byapplication of a persistent form of eugenol. As disclosed herein, theinventors have produced eugenol in a gel form as an “emulgel” that whenapplied to cured dental cement or resins in the mouth prolongs therelease of eugenol thus making the cured dental cement or resin lesshard and easier and safer to remove.

A debonding composition according to the invention will contain eugenolin a form that permits prolonged contact between a dental cement orresin and the eugenol in the composition, for example, in a preferredform contains eugenol and one or more surfactants, cosurfactants,pH-adjusting agents, preservatives, or other ingredients.

Eugenol.

Eugenol is phenylpropene, an allyl chain-substituted guaiacol and amember of the phenylpropanoids class of chemical compounds. Eugenoland/or its derivatives and isomers such as isoeugenol, methyl-eugenol oran isomer thereof may be employed in some embodiments of the invention.Eugenol is a liquid that quickly disperses when administered into themouth. In contrast, the invention provides eugenol in a form, such as agel, that once applied persists and releases eugenol over a period oftime thus providing for continuing softening of dental cement or resinthat fix metal bracket or other dental appliances or prosthetics toteeth. In preferred embodiments of the invention a debonding compositionwill be in the gel form containing eugenol in an effective amount whichmay range from about 0.5-25 wt % based on the weight of the debondingcomposition. The eugenol content range includes all subranges andintermediate values including 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12.5,15, 17.5, 20, 22.5, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85,90, 95 or <100%. In most embodiments, the content of eugenol will notexceed that necessary to maintain a composition in a stable, easilyapplicable gel form.

Effective Amount.

As used herein, the term “effective amount” means a quantity of eugenolrequired to reduce the Vickers hardness of a dental cement or resin, toreduce force needed to debond a metal bracket or other dental prostheticfrom the surface of a tooth, or to reduce residual dental cement orresin on surfaces of teeth that remain after removal of a dental bracketor prosthetic.

Gel Base.

A gel base and its content of ingredients are selected to provide forsustained release of eugenol after application to a dental cement orresin. Gel bases include, but are not limited to, an anionic polymer,such as a polycarboxylate, poly(acrylic acid, which may be crosslinked,polyalkenyl ethers, divinyl glycol, 1:4 to 4:1 copolymers of maleicanhydride or maleic acid with another polymerizable ethylenicallyunsaturated monomer such as methyl vinyl ether/maleic anhydride (PVM/MA)copolymer. A gel base may be in free or salt form. In preferredembodiments of a debonding composition (e.g., emulgel) of the invention,the gel base may comprise a carbomer (e.g., Carbopol 934, Carbopol 940),hydroxy propyl methyl cellulose (e.g., HPMC K4M), polaxamer, carboxymethyl cellulose sodium or other gelling agents in an amount rangingfrom 0.5-10 wt %, which range includes all subranges and intermediatevalues including 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35,40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, or 95 wt %.

Surfactants.

Include nonionic surfactants such as poloxamers, polysorbates, andmixtures thereof. In some preferred embodiments one or more surfactantssuch as a polysorbate (e.g., Tween 80/polysorbate 80, Tween20/polysorbate 20), cremophore (e.g., Cremophorc RH40) are incorporatedin an amount ranging from 1 to 40 wt %, which range includes allsubranges and intermediate values including about 1, 2, 3, 4, 5, 6, 7,8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, or 65 wt %.

Cosurfactants.

In some preferred embodiments one or more co-surfactants such aspolyethylene glycol, propylene glycol, glycerol are added in an amountranging from 2.0-30 wt %, which range includes all subranges andintermediate values including about 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20,25 and 30 wt %.

pH-Adjusting Agents.

A buffer or other pH adjusting agent such as sodium hydroxide ortriethanol amine may be added in an amount sufficient to titrate the pHof the emulgel or other composition of the invention to fall within therange of about pH 4-8.0 and preferably within the range of about pH.6.0-6.5. This range includes all subranges and intermediate valuesincluding 4, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, and 8.0. pH may also beadjusted based on the oral pH of a subject. Saliva usually has a pHranging from 6.2 to 7.6 and pH of a composition of the invention may bematched to that of the oral pH or to be about 0.25, 0.5, 0.75, or 1.0 pHunits below or above it.

Preservatives.

A debonding composition according to the invention may contain one ormore preservatives to extend its useful life, prevent oxidation, orprevent microbial contamination. In some preferred embodiments one ormore preservatives such as a paraben (e.g., methyl-paraben,propy-1-paraben, or butyl-paraben) are added in an amount ranging from0.01 to 0.45 wt %, which range includes all subranges and intermediatevalues including at least about 0.01, 0.02, 0.03, 0.04, 0.05, 0.075,0.1, 0.2, 0.25, 0.3, 0.4, and 0.45 wt. %.

Other Components.

Other ingredients such as at least one buffer or pH-adjusting agent(e.g., acidifier or basifier), sweetener, analgesic, cooling agent(e.g., menthol, camphor, peppermint oil), soothing agent (e.g.,2-ethoxylbenzoic acid, 2-methyl-4-methyphenol, tall oil, rosin or pinegum; KNO₃), anti-inflammatory agent, antibiotic, astringent, lubricants,electrolytes (e.g., sodium potassium, magnesium, calcium; chloride,fluoride, iodide, bicarbonate or phosphate) or solvent (e.g., DMSO) mayoptionally be incorporated into a eugenol-containing gel that is usedfor debonding. Particles, such as microparticles or nanoparticles, orliposomes, encapsulating or incorporating eugenol that is released overa preselected period of time such as those disclosed herein may also beincorporated into a gel or non-gel composition according to theinvention. Such particles or liposomes may be produced by methods knownin the art or those disclosed and incorporated by reference to Hudson,et al., U.S. Pat. No. 9,102,573, to Fountain, U.S. Pat. No. 9,364,434 orto Shefer, et al., U.S. Pat. No. 7,670,627. In some embodiments one ormore of these other components are present, in others they are absent.

Eugenol-Containing Temporary Adhesives, Viscous Forms and Other Non-GelForms.

Eugenol may also be compounded in a non-gel form that adheres or bindsto dental cement or resin such as that fixing a metal brace to an enamelsurface of a tooth. Like gel forms these are formulated to temporarilyadhere and prolong the release of eugenol into a dental cement or resin.In some embodiments a composition according to the invention may be in asolid or semi-solid form, such as a hardened coating, paint, varnish, orputty out of which eugenol can leach, or in the form of an aerosol,vapor, gas, or ionized gas, such as an aerosol spray containing eugenolthat is applied to, sprayed on, pressure-sprayed on, or pressurized intoa hardened or cured dental cement or resin.

Units of Weight.

Unless otherwise specified, all percentages and amounts expressed hereinand elsewhere in the specification refer to percentages by weight andthe amounts given are based on the weight of the material andweight-percent (wt. %) is based on the amount of a material divided bythe total weight of the debonding composition.

Viscosity.

Viscosity of a liquid, semi-liquid or semi-solid composition of theinvention can be measured in units of centipoise (“cP”) or onemillipascal-second (mPa·s). A composition according to the invention maybe formulated at a viscosity sufficient to contact eugenol, isoeugenol,methyl-eugenol or an isomer thereof with a cured or hardened orthodonticor dental cement or resin for a time sufficient to reduce its Vickershardness, for example, to reduce Vickers hardness to 90, 80, 70, 60, 50,40, 30, 20, 10 or less. Preferably, such a composition will be in theform a gel or viscous liquid which can easily be applied to or contactedwith dental cement or resin bound to teeth, orthodontic brackets, orother dental fixtures. Viscosity of a composition according to theinvention generally range from 1,000 to 100,000,000 centipoise includingall intermediate subranges and values such as at least 1,000, 5,000,10,000, 50,000, 100,000, 500,000, 1,000,000, 5,000,000, 10,000,000,50,000,000 and 100,000,000 centipoise (cP). Compounds having viscositieswithin this range include water (I cP), blood or kerosene (10 cP),antifreeze or ethylene glycol (15 cP), motor oil SAE 10 or corn syrup(50-100 cP), motor oil SAE 30 or maple syrup (150-200 cP), motor oil SAE60 or glycerin (1,000-2,000 cP), corn syrup or honey (2,000-3,000 cP),blackstrap molasses (5,000-10,000 cP), chocolate syrup (10,000-25,000cP), ketchup or prepared mustard (50,000-70,000 cP), tomato paste orpeanut butter (150,000-2,000,000 cP), shortening or lard(1,000,000-10,000,000 cP), caulking compound (5,000,000-10,000,000 cP)and window putty (100,000,000 cP). In some embodiments, the viscosity ofa composition of the invention ranges from about 1,000 centipoise (cPs)to about 10,000,000 cPs, in other embodiments range from about 10,000 cPto about 1,000,000 cPs, and in other embodiments from 100,000 cPs toabout 500,000 cPs. These ranges include all subranges and intermediatevalues. In other embodiments a eugenol-containing composition accordingto the invention may be in a liquid or semi-liquid forms, such as thinliquid (e.g., 1-15 cP), thick liquid (>15 cP), foam, gel, emulsion,ointment, salve, or paste. The rate of release of eugenol by an emulgelmay be modulated by increasing or decreasing its concentration in theemulgel or by raising or lowering the viscosity of the emulgel.

Oral Application.

A gel containing eugenol or a eugenol composition in another viscous orother form that is capable of adhering around metal brackets or otherdental appliances affixed to teeth with a bonding cement or resin may beapplied by various known methods, for example, by application with adental tool, syringe, brush or spray.

Such a eugenol-containing composition must be capable of continuouslyexposing the bonding cement or resin to the eugenol it contains for aperiod of time sufficient for significant dehardening of the cement orresin. For example, a eugenol-containing gel or other composition willbe formulated so as to persist on or around the dental cement or resinand release eugenol into it for a period of time ranging from at least5, 10, 15, 20, 30, or 60 mins, or for at least 1, 2, 3, 4, 5, 6, 7, 8,9, 10, 12, 16, 20, 24 hours. In some cases, a eugenol-containing gel orother composition may be reapplied once or more than once at intervals,for example at intervals of 15, 30, or 60 mins, of 2, 4, 6, 8, or 12hours.

In some embodiments, a composition of the invention may be applied underpressure or by impacting particles or droplets of the compositionagainst dental cement or resin, in others it is applied under normalatmospheric pressure, for example, by painting or coating it on a dentalcement or resin or by soaking a dental cement or resin in it. In otherembodiments, a eugenol-containing composition may be formulated in abinary form comprising two or more liquids than when mixed form a solidcast around dental cement or resin on teeth or dental fixtures. However,preferably, a composition according to the invention will be in gelform, such as in an emulgel as disclosed herein.

In some embodiments, prior to application of a eugenol-containingcomposition, the surface containing the dental cement or resin may bebrushed, buffed, polished, washed or etched to remove microbial orchemical coatings (such as biofilm or adherent proteins, carbohydratesor lipids).

Assessment of Debonding Strength.

Debonding strength was assessed substantially according to a methoddescribed by Bishara et al. who developed a clinically representativemethod using debonding pliers mounted on the Instron Universal Machine.Bishara debonding force was described as being similar to the forceapplied during a diametral compression test for tension. The diametralcompression test was considered as a way of indirectly measuring thetensile strength of a material that exhibited very limited plasticdeformation such as ceramics, composites, and enamel. The debondingpliers were unique in that they applied the force at thebracket-adhesive interface on both sides of the bracket simultaneouslyas a bilateral load. Bishara further compared the differences betweenthe actual forces generated during bracket removal in the clinicalsetting and the shear forces applied during laboratory testing fordebonding ceramic brackets. Their results indicated that debonding withpliers required the application of 30% less force to the enamel surfacethan debonding with shear forces as tested in the laboratory.

There were no significant differences in the Adhesive Remnant Index(ARI) of the two groups, i.e. where the bond failures occurred in theirstudy. Thus, Bishara suggested that applying the load to the two sidesof the bracket increased the chances of starting a crack and propagatingit in the brittle adhesive causing debonding to occur at a lowerdebonding force. Horiuchi et al, also adopted such method in assessingthe bond strength.

In a previous study, a finite element analysis showed that the leastamount of stress on enamel during debonding occurred when applyinglateral rotation force on the bracket with a debonding plier asdescribed by Holberg C, Winterhalder P, Holberg N, Wichelhaus A,Rudzki-Janson I. “Orthodontic bracket debonding: risk of enamelfracture”. Clin Oral Investig 2014; 18:327-334, incorporated herein byreference in its entirety. Lateral rotation was defined in Holberg etal. study as the pliers exerting force on the occlusal and gingivalparts of the brackets and causing lateral rotation at debonding. Theforce of the pliers in the examples described herein was applied at thebracket-adhesive interface in an occluso-gingival direction (bilateralload). However, due to the thin bracket-adhesive interface, the slippageof the plier blades was common and a lateral rotation stress was mostlyapplied during debonding.

In the examples herein and as a referent resin, the inventors used awidely-used and copied resin cement: Trans Bond XT® manufactured by 3Mcompany, which is incorporated by reference to http://_multimedia.3m.com/mws/media/l11911O/transbond-xt-light-cure-orthodontic-adhesive-ifu.pdf?&fn=TransbondXT_011-519-1_ML_1205.p(last accessed Aug. 28, 2017). A Trans Bond XT® product is alsodescribed by the 3M products on sale in 2016 or 2017 bearing this nameand trademark. However, the method of the invention may be used to helpremove other similar types of resin cements or other kinds of dentalcements.

Fourier-Transform Infrared Spectroscopy FTIR Spectroscopy.

This technique is capable of detecting the stretching vibrations ofcarbon-carbon double bonds involved in polymerization and thus it provedits feasibility to monitor the degree of conversion of orthodontic resincement. Fourier-transform infrared spectroscopy FTIR spectroscopy is awidely used technique for investigating materials in the gaseous, liquidor solid phase. It is based on the interaction between electromagneticradiation and natural vibrations of the chemical bonds among atoms thatcompose the matter. FTIR which can detect the stretching vibrations ofcarbon-carbon double bonds involved in polymerization. The methodtypically utilizes the height ratio of the peaks corresponding toaliphatic (1,637 cm-1) and aromatic (1,715 cm⁻¹) double bonds todetermine the DC. FTIR-ATR is more versatile than transmission FTIRbecause it eliminates the need of KBr (NaCl) plates, sectioning of thinwafers, or cure of the material in a thin film form. This simplifiessample preparation and, more importantly, allows the resin to be curedunder conditions closer to clinical cases. FTIR-ATR also has an edge onevaluating the degree of conversion over hardness test as it wasreported previously.

Objects Bound to Teeth with Dental Cement or Dental Resin.

These include, but are not limited to any type of orthodontic bracket,fixed orthodontic appliance, dental fixed appliance made of anymaterial, or dental prosthetic manufactured from any material which arebound to a tooth or teeth with a dental cement or dental resin. Examplesinclude orthodontic materials or devices, cemented laminates, veneers,fixed dental crowns, and fixed dental bridges.

EMBODIMENTS

Although specific embodiments have been illustrated and describedherein, any arrangement calculated to achieve the same purpose may besubstituted for the specific embodiments shown. This disclosure isintended to cover any and all adaptations or variations of variousembodiments. Combinations of the embodiments described herein and otherembodiments not specifically described herein will be apparent to thoseof skill in the art upon reviewing the above description.

One embodiment of the invention is directed to a composition having a pHranging from pH 6.0 to 8.0 comprising eugenol, at least one crosslinkedpolymer of acrylic acid or at least one other gelling agent, and atleast one polysorbate or at least one other surfactant; wherein theamount of eugenol is sufficient to reduce the Vickers hardness of acured or hardened orthodontic bonding adhesive cement or resin to avalue of 70 or less after contacting it for at least 10 mins and/or issufficient to reduce debonding force needed to remove a metal bracketfrom an enamel surface of a tooth. In other embodiments, one or more ofthe ingredients described above may be replaced with at least onefunctional equivalent. In some embodiments the pH may range from 5.0,5.5, 6.0, 6.5, 7.0, 7.5 or 8.0. Saliva usually has a pH ranging from 6.2to 7.6 and pH of a composition of the invention may be matched to thatof the oral pH or to be 0.25, 0.5, 0.75, or 1.0 pH units below or aboveit.

In some embodiments the composition of the invention will containeugenol, such as eugenol in the form of clove oil or synthetic eugenolin an amount ranging from about 0.5 to 10 wt %. This range includes allsubranges and intermediate values such as about 0.5, 0.75, 1.0, 1.5,2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5,9.0, 9.5 and 10. In other embodiments, the composition can contain anamount of eugenol within the above-mentioned range or a lower or higherof eugenol (e.g., 0.10, 0.25, 0.5, 1.0, 5.0, 10.0, 15, 20, 30, 40, 50,60, 70, 80, 90 or ≤100 wt % eugenol) provided that the selected amountis sufficient to reduce the Vickers hardness of a cured or hardenedorthodontic bonding adhesive cement or resin to a value of 100, 90, 80,70, 60, 50, 40, 30, 20 or less after contacting it for at least 10 minsand/or is sufficient to reduce debonding force needed to remove a metalbracket from an enamel surface of a tooth compared to an otherwiseidentical composition that does not contain eugenol or that containspeppermint oil or another volatile compound instead of eugenol. Thecomposition of the invention may be in solid, particulate, semi-solid,semi-liquid, liquid, droplet, aerosol, vaporous or gaseous form.

In some embodiments the eugenol-containing composition will containabout 0.5 to 10 wt % of one or more types of crosslinked polymers ofacrylic acid or Carbopol 934 or 940 and/or at least one hydroxy propylmethyl cellulose, polaxamer, or carboxy methyl cellulose sodium polymer.This range includes all subranges and intermediate values such as about0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0,7.5, 8.0, 8.5, 9.0, 9.5 and 10. However, a greater or lesser amount ofthese gelling agents is incorporated depending on the degree ofviscosity desired.

In other embodiments the composition will contain at least onesurfactant such as polysorbate including polysorbate 20 or polysorbate80, a cremophore (e.g., Cremophor®, Kolliphore®) produced by reactingethylene oxide with each mole of castor oil such as the compositiondescribed by CAS number 61791-12-6, or other non-toxic surfactant.Preferably, a surfactant is incorporated in an amount ranging from about1 to 40 wt % of the total weight of the composition. This range includesall subranges and intermediate values such as about 1.0, 1.5, 2.0, 2.5,3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5,10, 15, 20, 25, 30, 35 and 40.

In other embodiments, the composition will contain a co-surfactant suchas polyethylene glycol, propylene glycol, or glycerol, preferably in anamount ranging from 2 to 30 wt % based on the total weight of thecomposition.

In some embodiments, the composition will also contain a preservativesuch as a paraben (para-hydroxybenzoate which may be substituted with aC₁-C₆ or other alkyl group, such as methyl-paraben, propy-1-paraben, orbutyl-paraben) in an amount sufficient to inhibit microbial growth,prevent oxidation, or otherwise extend the useful life of thecomposition. Preferably, the content of the preservative ranges from0.01 to 0.45 wt % of the weight of the composition. This range includesall subranges and intermediate values such as about 0.01, 0.05, 0.1,0.15, 0.20, 0.25, 0.30, 0.35, 0.40 and 0.45.

In some preferred embodiments a composition of the invention includes5-15 wt % clove oil, 20-30 wt % polysorbate 20 (TWEEN 20®), 10-15 wt %propylene glycol, 1-3 wt % crosslinked polyacrylate polymer and water.

The viscosity and eugenol content of a composition according to theinvention may vary depending in part on the site, oral pH, age orchemical composition of a cement or resin, and intended length ofapplication time. In some embodiments the viscosity will range fromabout 1,000 to 5,000 cP in others the viscosity will exceed 5,000 cP.This range includes all subranges and intermediate values such as 1,000,1,250, 1,500, 1,750, 2,000, 2,500, 3,000, 3,500, 4,000, 4,500, and5,000.

Another embodiment of the invention is directed to a method for removinga dental adhesive or cement from a tooth or other dental substrate,dental appliance, or prosthetic comprising contacting the dentaladhesive or cement with eugenol, isoeugenol, methyl-eugenol or an isomerthereof. Preferably, the composition used in this method will containeugenol, but other eugenol-like compounds may also be used or combinedwith eugenol. In this method the eugenol-containing composition isapplied to a dental adhesive or cement bonds an orthodontic bracket toan enamel surface of a tooth with the eugenol preferably contained in agel, such as a gel including eugenol, at least one surfactant, and atleast one gelling agent. The eugenol-containing composition may also beapplied as a varnish or as an adhesive coating that sticks to the dentaladhesive or cement. In some embodiments, this method will reduce theVickers hardness of the dental adhesive or cement below 90, 80, 70, 60,50, 40, 30, 20 or 10. In some embodiments this method will reduce the toreduce debonding force needed to remove a metal bracket from an enamelsurface of a tooth by 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100% ormore compared to an otherwise identical composition not containing theeugenol or containing an otherwise identical composition containing adifferent active ingredient, such as peppermint oil. For example, sheerdebonding force may be reduced from more than 6 mPA to less than 5, 4.5,4, 3.5, 3, or 2.5 mPA as shown by FIG. 4. Dental cement or resin mayalso be debonded using the method of the invention from other dentalsubstrates, such as from dentin, enamel, metal, ceramic, porcelain, andzirconia substrates.

In another embodiment, the method according to the invention willproduce debonded teeth having an adhesive remnants index (ARI) scores of0, 1, 2 or 3 and comprise removing these remnants. ARI scores may varydepending on type of cement or resin applied, content of eugenol in adebonding composition, and amount of time cement or resin is contactedwith a debonding composition. Debonded teeth may be characterized by ARIscores of 0, 1, 2, 3 and/or 4 for at least 0, 12.5, 25, 50, 62.5, 75, or100% of teeth or intermediate values within this range based on thenumber of teeth debonded.

In some embodiments, the method will involve brushing, buffing,polishing, washing or etching or otherwise cleaning a contact surface ofthe dental cement or resin to remove microbial or chemical coatingsprior to contacting it with the eugenol in the form of a gel. In otherembodiments, residual dental cement or resin is removed after debondingof the dental bracket, appliance, or prosthetic. Such removal isgenerally easier and safer because eugenol has softened the residuematerial permitting it to be more safely removed.

Another embodiment of the invention represents a kit containing aeugenol-containing composition as disclosed herein, a tray suitable forretaining the composition and contacting the composition with at leastone dental fixture bonded with a dental cement or resin to teeth, and,optionally, packaging materials and/or instructions for use. This kitmay contain a tray that is customized or cast to fit over a subject'steeth and brackets or other dental fixtures.

Another embodiment is directed to a method for debonding metal brackets,a dental appliance or dental prosthetic by filling a tray with acomposition comprising eugenol, or a eugenol gel or othereugenol-containing composition; fitting the tray over teeth that arebonded to metal brackets, a dental appliance, or a dental prosthetic fora time sufficient to reduce Vickers hardness of a dental cement or resinbinding the metal brackets, dental appliance or dental prosthetic to theteeth, and debonding the metal brackets, a dental appliance, or a dentalprosthetic from the teeth.

In another embodiment, the invention is directed to curable orhardenable dental cement or resin that is “preloaded” with an amount ofeugenol, isoeugenol, methyl-eugenol or an isomer thereof that does notnegatively affect is ability to bond dental brackets, appliances orprosthetics to dental surfaces, but that is easier or faster to removeby contacting it debonding with eugenol, such as a eugenol emulgel toincrease a threshold amount of eugenol in the cured dental cement orresin to one that softens it. This curable or hardenable dental cementor resin can comprise a conventional dental cement or resin such asthose known in the art or described herein to which eugenol is added.Eugenol is added in an amount that does not significantly reduce theability of the cement or resin to bond metal braces, brackets or dentalfixtures to teeth, but that facilitates removal of the cement or resinwith a eugenol-containing composition of the invention. This cement orresin may thus be used for bonding and then in combination with aeugenol-containing composition of the invention to facilitate fast andsafe debonding of dental brackets and other fixtures from enameledsurfaces of teeth. In one embodiment components for forming or applyinga cured dental cement or resin containing eugenol for use in dentalbonding, and those of an emulgel or components for making it for lateruse in debonding are combined in a single kit. In some embodiments oneor more of eugenol, isoeugenol, methyl-eugenol or an isomer thereof areincorporated into the dental cement or resin.

EXAMPLES

The examples and illustrations included herein show, by way ofillustration and not of limitation, specific embodiments in which thesubject matter may be practiced. As mentioned, other embodiments may beutilized and derived there from, such that structural and logicalsubstitutions and changes may be made without departing from the scopeof this disclosure. The following examples illustrate various aspects ofthe present invention. They are not to be construed to limit the claimsin any manner whatsoever.

The inventors assessed the effect of eugenol on the orthodontic adhesivematerial and the debonding behavior of metal brackets with an objectiveof developing a clinically applicable method for using eugenolcompositions debond orthodontic brackets. As the bracket-adhesiveinterface in metal brackets is very thin, eugenol was prepared in theform of gel to ensure its retention around the bracket. Theeugenol-containing gel was applied for an in-clinic applicable period of10 min and an out-clinic period 24 hr.

Example 1 Eugenol Emulgel Preparation

An emulgel was prepared from 10 wt % clove oil, 27 wt % polysorbate 20(TWEEN 20®), 13 wt % propylene glycol, 1.5 wt % crosslinked polyacrylatepolymer and 48.5 wt % water. The crosslinked polyacrylate polymer wasCARBOPOL 934® which is incorporated by reference tohttp://_www.surfachem.com/carbopol-934, last accessed Jul. 23, 2017.

A solubilized system gel was prepared by first mixing propylene glycolwith clove oil to produce an oily phase. An aqueous phase was thenprepared by incorporation of TWEEN 20® with a portion of deionizedwater. For the preparation of gelling phase, CARBOPOL 934@ was dispersedusing an IKA UTRATURAX T10® (Switzerland) homogenizer and neutralized toa pH 6.0-6.5 with 0.5 M sodium hydroxide. The aqueous phase was addeddrop wise to the oily phase while mixing until a clear homogenoussolubilized system formed. The gelling phase was then added slowly tosolubilized system until a homogenous clear/opalescent gel formed.

Example 2 Application of the Eugenol Emulgel on Bonded Dental Brackets

Bonded brackets to the teeth were fixed onto a dental model(Nissin-Dental, Tokyo, Japan) using high fusing impression compound.Alginate impressions were made for all models having the teeth withbonded brackets attached to it. Casts were prepared and each toothbearing bracket on the dental cast was blocked with paraffin wax toobtain space for eugenol-containing emulgel delivery. A polypropylenesheet (Easy Vac-Gasket, 3A MEDES, Korea) was vacuum-adapted to each castwith a vacuum-forming machine (Henry Schein, Henry Schein Inc., NY,USA). From the vacuum adapted sheet, individual trays were made to fitonto the tooth surfaces to cover the complete arch of the teeth on themodel and were trimmed to be approximately 1 mm above the gingivalmargin. The eugenol emulgel was applied to the brackets bonded to theteeth using the customized trays and then the whole model was placed ina container having distilled and placed in incubator for 24 hours.

Micro-Hardness Assessment.

One hundred and twenty Transbond composite resin and Transbond primerdiscs (3M, St. Paul, Minn., USA) were prepared by filling a plastic mold(10 mm inner diameter×2 mm depth). The exposed surfaces were thencovered by Mylar matrix strips and light cured using a light curing unit(Luxor lamp, ICI Plc, Macclesfield, Cheshire, UK). All specimens werestored in distilled water at 37° C. for 1 day to ensure completepolymerization of the resin materials.

The discs were divided into six groups, three groups for the Transbondcomposite and three groups for the Transbond primer (n=20 each) asfollows; control, eugenol 10 min application and eugenol 24 hrapplication.

In the two eugenol groups, eugenol-containing emulgel was applied to thesurface of the discs using a brush and left for 10 min and 24 hr beforebeing washed away with water emitted from a triple syringe. All discswere then subjected to ten indentations, with a load of 200 g for 20 secusing a micro-hardness tester (HMV-2000 Shimadzu, Japan) and the Vickershardness values were recorded.

Bond Strength Assessment.

Based on 80% power of test, 45 sound extracted premolars, with noobvious enamel cracks were collected and stored in distilled water.

Teeth were then cleaned, polished with non-fluoridated pumice and rubberprophylactic cups for 15 sec, rinsed with water spray for 10 sec andthen dried with oil-free compressed air for 10 sec.

The buccal surfaces were etched with 37% phosphoric acid solution for 30sec according to the manufacturer's instructions, rinsed with waterspray for 20 sec and then dried with oil-free compressed air for 20 sec.

All teeth were bonded with metal brackets under constant load usingTransbond XT light cured composite resin (3M, St. Paul, Minn., USA), andstored in distilled water at 37° C. in an incubator for one week toensure complete polymerization of the adhesive resin.

The sample was then randomly divided into three groups (n=15 each):control, eugenol 10 min application, and eugenol 24 hr application.

All teeth were then debonded with a narrow blade debonding plier (AEZDebonding Orthodontic Plier, Ormco Corporation, USA) mounted on anInstron Universal Testing machine according to the modified methodfollowed by Bishara et al., Horiuchi et al., and Hama et al. Bishara SE, “Comparisons of the effectiveness of pliers with narrow and wideblades in debonding ceramic brackets”. Am J Orthod Dentofacial Orthop1993; 103:253-257; Bishara, et al., “Debonding forces applied to ceramicbrackets simulating clinical conditions”, Angle Orthod. 1994;64:277-282; Horiuchi S, Kaneko K, Mori H, Kawakami E, Tsukahara T,Yamamoto K, et al. “Enamel bonding of self-etching and phosphoricacid-etching orthodontic adhesives in simulated clinical conditions:debonding force and enamel surface”. Dent Mater J 2009; 28:419-425; andHama T, Namura Y, Nishio Y, Yoneyama T, Shimizu N. Effect of orthodonticadhesive thickness on force required by debonding pliers. J Oral Sci2014; 56:185-190, each of which is incorporated herein by reference intheir entirety. Such method was chosen because it simulates the clinicalsituation. The stainless steel blades of the pliers were placed at thebracket-adhesive interface, and a squeezing action at a crosshead speedof 0.5 mm/min was applied to the plier at room temperature until bondfailure occurred and the debonding strength was recorded.

The debonding force by the Instron was applied at a predeterminedconstant distance on the arms of the plier. Thus, the actual debondingstrength was calculated using the following formula:The actual debonding strength=measured strength(by the Instronmachine)×(b/a)Where (a) is the distance between the blades of the plier at thebracket-adhesive interface and the fulcrum of the plier, while (b) isthe distance from where the force is applied on the plier's arms by theInstron machine to the fulcrum of the plier (FIG. 1). The conversionfactor (b/a) used in this study was calculated to be 0.55.

All teeth were examined under a stereomicroscope at 10×, and 20×magnification for the residual adhesives remaining on the buccal enamelsurfaces.

The amount of adhesive remnant was then scored using the modifiedAdhesive Remnant Index (ARI) as follows:

Score 0: no retained resin (0%).

Score 1: ≤50% retained resin on the enamel surface (>0%-≤50%).

Score 2: >50% retained resin on the enamel surface (>50%-<100%).

Score 3: all resin retained on the enamel surface with bracket imprint(100%).

Additional details of ARI scoring are incorporated by reference to ÃrtunJ, Bergland S. Clinical trials with crystal growth conditioning as analternative to acid-etch enamel pretreatment. Am J Orthod 1984;85:333-340.

FTIR/ATR Analysis.

Fourier-transform infrared (FTIR) spectrometer (Thermo Nicolet™ iS™ 5FT-IR Spectrometer, Thermo Electron Corporation, MA, USA) was performedwith the attenuated total reflectance (ATR) accessory and a plate ofzinc selenite crystal at 450. All measurements were obtained under thefollowing conditions: resolution of 4 cm⁻¹ and four internal scans perreading. For each cured resin, the same non-cured resin served as thecontrol. After obtaining the readings for the non-cured resin; curing ofthe examined two types of resins was carried out according tomanufacturer instructions, holding the light curing unit at constantdistance of 2 mm from the examined resins. Each of the cured resins werenumbered and randomly assigned into three groups; Control (stored indistilled water 24 hours), Eugenol 10 min (application of eugenol for 10mins; washed and then stored in distilled water for 24 hours), andEugenol 24 hr (application of eugenol for 24 hours then washing bydistilled water).

Before the first reading and between each new set of measurements of thenon-cured resin (monomer) and cured resin (polymer), a baseline spectrumbackground was obtained with all the artefacts that would be used beforecuring the Transbond XT. The purpose of this first measurement was todetermine the spectra of the artifacts used in the measurements, whichwould be deducted by the equipment in the subsequent monomer and polymermeasurements of each specimen as described by Kawabata R, Hayakawa T,Kasai K. “Modification of 4-META/MMA-TBB resin for safe debonding oforthodontic brackets—influence of the addition of degradable additivesor fluoride compound”. Dent Mater J 2006; 25:524-532, incorporatedherein by reference in its entirety.

The light was applied on the opposite side of the infrared reading beamscan. Between each set of monomer/polymer spectra, the crystal plate ofthe ATR accessory was cleaned with absorbent paper and acetone and thendried with air blower, so that there would be no residues to prejudicethe new set of monomer/polymer spectrum measurements.

The measured spectra for all systems contained the following majorpeaks: stretching vibrations of aliphatic C═C at 1,638.6 cm⁻¹, of C═O at1730 cm⁻¹, of C—H groups at −2,900 cm⁻¹ and of O—H at N 3,500 cm⁻¹. Tounderstand the effect of Eugenol on the primer and the composite resin,ratios of the absorbance intensities (AI) of these peaks to that of thearomatic C═C at 1609.4 cm-1 were calculated. Aromatic C═C bonds areconsidered stable in resins. The C═C bonds of benzene are stable,probably as a result of delocalized electrons in which resonance (ordelocalization) energy is required to hold them in place. Each set ofscraping samples from the specimen was analyzed two times. A mean andstandard deviation often analyses for each group (five specimens) werecomputed and a statistical analysis of AI was performed.

Statistical Analysis.

Data were analyzed using descriptive statistics to report the means andstandard deviations for the microhardness values, shear bond strength(MPa), and the ARI scores for the three groups. Inferential statisticsfor mean comparison in microhardness and shear bond strength values wasconducted using One-way ANOVA and Tukey's Post Hoc test. Kruskal Wallistest was conducted for ARI scores comparison between the three groups.All data were analyzed using SPSS statistical analysis software program(Version 16, SPSS Inc., Chicago, USA). Significance level was set at(p<0.05).

Microhardness.

The mean Vickers hardness value for the control group (91.41+/−6.95) wassignificantly higher than the two eugenol groups; 10 min application(69.18+/−6.95) and 24 hr application (65.37+/−8.66) at p<0.05 (FIG. 2).

Debonding Strength.

The eugenal 24 hr application showed significantly lower mean shear bondstrength (2.29+/−0.69 MPa) than the other two groups: control(6.68+/−1.73 MPa) and eugenol 10 min group (4.72+/−2.48 MPa) at p<0.05(FIG. 4, Table 1).

Adhesive Remnants.

Kruskal Wallis test revealed no significant difference in the adhesiveremnant scores after debonding between the three groups (p>0.05). Morethan 50% of the sample in all groups had ARI score 1 (≤50% retainedresin on the enamel surface). Concomitantly, none of the sample had ARIscore (0) where no adhesive remained after debonding (FIG. 5, Table 2).

FTIR/ATR Results.

Ratios of Absorbance intensities for the aliphatic C═C (1,638.6 cm⁻¹)and the C—O at 1730 cm⁻¹ to that of the aromatic C═C peak (1,609 cm⁻¹)decreased significantly upon application of the emulgel on the XT resinsurface and the XT primer for 24 hr at p<0.05. There was no significanteffect p<0.05 on the aforementioned ratios when the emulgel was appliedon the XT resin surface and the XT primer for 10 minutes.

Comparative Advantage of Debonding Method of the Invention.

The effects of other chemical solvents, such as peppermint oil on thedebonding of orthodontic brackets were described by Larmour C J,Chadwick R G. “Effects of a commercial orthodontic debonding agent uponthe surface microhardness of two orthodontic bonding resins”. J Dent1995; 23:37-3, incorporated herein by reference in its entirety.

Larmour, in his two studies, assessed the effectiveness of a viscous gelcontaining a derivative of peppermint oil that was marketed in the 90'sas a post-debonding agent (P-de-A, Oradent Ltd, Eton, Berks. UK) fordebonding ceramic brackets. They found that a 60 sec application ofpeppermint gel can have a significant positive effect on the debondingstrength and the failure of bond at the adhesive/enamel interface whendebonding ceramic brackets. On the other hand, Larmour & Chadwickreported no significant effect of such product on the microhardness ofTransbond light cured adhesive material.

In comparison to these studies, the inventors show a significantreduction in the microhardness of the Transbond XT light cured compositeresin after both 10 min as well as 24 hr of eugenol application and thatdebonding strength was significantly reduced after 24 hr of eugenolapplication.

The amount of adhesive remnant was not significantly changed with theuse of eugenol. It can also be noted that the mean hardness valuereported in this study was in the range of (65.37-69.18) while the meanvalue after 180 sec of peppermint oil application was (112.02+/−13.87).These results indicate that eugenol seems to reduce the microhardnesssignificantly more than peppermint oil.

Eugenol, in the current study, is found to have an effect on debondingmetal brackets after 24 hr. However, a 10 min application of eugenol, asdesigned in this study, did not reduce the debonding strength and theadhesive remaining after debonding metal brackets to a level that iscompetitive to the control.

On the other hand, the microhardness results for the primer and thecomposite showed decreased values after the 10 min and 24 hr of eugenolapplication; the obtained results may be explained as follows; Eugenolemulgel exerted an immediate softening effect on the XT resin cement andon the XT polymerized primer, however, these softening effects were notenough to weaken the bond strength of the metallic brackets bonded tothe enamel surfaces. The eugenol softening effects on the resin cementand on the primer were accentuated after 24 hr which were manifested asa significant decrease in bond strength after 24 hr of eugenolapplication. The aforementioned hypothesis was supported by the FTIRresults which showed that the 10 min eugenol application did not showdetectable chemical changes for the 10 min eugenol group while, asignificant changes for FTIR peaks were observed after the 24 hr eugenolapplication.

As disclosed here the eugenol-containing compositions of the inventionsignificantly reduced the microhardness of adhesive orthodontic bondingresins and significantly decrease the debonding strength of metalbrackets, thus providing an effective and safer way to remove dentalapparatus from teeth.

Terminology

Terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention.

The headings (such as “Background” and “Summary”) and sub-headings usedherein are intended only for general organization of topics within thepresent invention, and are not intended to limit the disclosure of thepresent invention or any aspect thereof. In particular, subject matterdisclosed in the “Background” may include novel technology and may notconstitute a recitation of prior art. Subject matter disclosed in the“Summary” is not an exhaustive or complete disclosure of the entirescope of the technology or any embodiments thereof. Classification ordiscussion of a material within a section of this specification ashaving a particular utility is made for convenience, and no inferenceshould be drawn that the material must necessarily or solely function inaccordance with its classification herein when it is used in any givencomposition.

As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise.

It will be further understood that the terms “comprises” and/or“comprising,” when used in this specification, specify the presence ofstated features, steps, operations, elements, and/or components, but donot preclude the presence or addition of one or more other features,steps, operations, elements, components, and/or groups thereof.

As used herein, the term “and/or” includes any and all combinations ofone or more of the associated listed items and may be abbreviated as“/”.

Links are disabled by insertion of a space or underlined space before“www” and may be reactivated by removal of the space.

As used herein in the specification and claims, including as used in theexamples and unless otherwise expressly specified, all numbers may beread as if prefaced by the word “substantially”, “about” or“approximately,” even if the term does not expressly appear. The phrase“about” or “approximately” may be used when describing magnitude and/orposition to indicate that the value and/or position described is withina reasonable expected range of values and/or positions. For example, anumeric value may have a value that is +/−0.1% of the stated value (orrange of values), +/−1% of the stated value (or range of values), +/−2%of the stated value (or range of values), +/−5% of the stated value (orrange of values), +/−10% of the stated value (or range of values),+/−15% of the stated value (or range of values), +/−20% of the statedvalue (or range of values), etc. Any numerical range recited herein isintended to include all subranges subsumed therein.

Disclosure of values and ranges of values for specific parameters (suchas temperatures, molecular weights, weight percentages, etc.) are notexclusive of other values and ranges of values useful herein. It isenvisioned that two or more specific exemplified values for a givenparameter may define endpoints for a range of values that may be claimedfor the parameter. For example, if Parameter X is exemplified herein tohave value A and also exemplified to have value Z, it is envisioned thatparameter X may have a range of values from about A to about Z.Similarly, it is envisioned that disclosure of two or more ranges ofvalues for a parameter (whether such ranges are nested, overlapping ordistinct) subsume all possible combination of ranges for the value thatmight be claimed using endpoints of the disclosed ranges. For example,if parameter X is exemplified herein to have values in the range of 1-10it is also envisioned that Parameter X may have other ranges of valuesincluding 1-9, 2-9, 3-8, 1-8, 1-3, 1-2, 2-10, 2.5-7.8, 2-8, 2-3, 3-10,and 3-9, as mere examples.

As used herein, the words “preferred” and “preferably” refer toembodiments of the technology that afford certain benefits, undercertain circumstances. However, other embodiments may also be preferred,under the same or other circumstances. Furthermore, the recitation ofone or more preferred embodiments does not imply that other embodimentsare not useful, and is not intended to exclude other embodiments fromthe scope of the technology. As referred to herein, all compositionalpercentages are by weight of the total composition, unless otherwisespecified. As used herein, the word “include,” and its variants, isintended to be non-limiting, such that recitation of items in a list isnot to the exclusion of other like items that may also be useful in thematerials, compositions, devices, and methods of this technology.Similarly, the terms “can” and “may” and their variants are intended tobe non-limiting, such that recitation that an embodiment can or maycomprise certain elements or features does not exclude other embodimentsof the present invention that do not contain those elements or features.

Although the terms “first” and “second” may be used herein to describevarious features/elements (including steps), these features/elementsshould not be limited by these terms, unless the context indicatesotherwise. These terms may be used to distinguish one feature/elementfrom another feature/element. Thus, a first feature/element discussedbelow could be termed a second feature/element, and similarly, a secondfeature/element discussed below could be termed a first feature/elementwithout departing from the teachings of the present invention.

Spatially relative terms, such as “under”, “below”, “lower”, “over”,“upper”, “in front of” or “behind” and the like, may be used herein forease of description to describe one element or feature's relationship toanother element(s) or feature(s) as illustrated in the figures. It willbe understood that the spatially relative terms are intended toencompass different orientations of the device in use or operation inaddition to the orientation depicted in the figures. For example, if adevice in the figures is inverted, elements described as “under” or“beneath” other elements or features would then be oriented “over” theother elements or features. Thus, the exemplary term “under” canencompass both an orientation of over and under. The device may beotherwise oriented (rotated 90 degrees or at other orientations) and thespatially relative descriptors used herein interpreted accordingly.Similarly, the terms “upwardly”, “downwardly”, “vertical”, “horizontal”and the like are used herein for the purpose of explanation only unlessspecifically indicated otherwise.

When a feature or element is herein referred to as being “on” anotherfeature or element, it can be directly on the other feature or elementor intervening features and/or elements may also be present. Incontrast, when a feature or element is referred to as being “directlyon” another feature or element, there are no intervening features orelements present. It will also be understood that, when a feature orelement is referred to as being “connected”, “attached” or “coupled” toanother feature or element, it can be directly connected, attached orcoupled to the other feature or element or intervening features orelements may be present. In contrast, when a feature or element isreferred to as being “directly connected”, “directly attached” or“directly coupled” to another feature or element, there are nointervening features or elements present. Although described or shownwith respect to one embodiment, the features and elements so describedor shown can apply to other embodiments. It will also be appreciated bythose of skill in the art that references to a structure or feature thatis disposed “adjacent” another feature may have portions that overlap orunderlie the adjacent feature.

The description and specific examples, while indicating embodiments ofthe technology, are intended for purposes of illustration only and arenot intended to limit the scope of the technology. Moreover, recitationof multiple embodiments having stated features is not intended toexclude other embodiments having additional features, or otherembodiments incorporating different combinations of the stated features.Specific examples are provided for illustrative purposes of how to makeand use the compositions and methods of this technology and, unlessexplicitly stated otherwise, are not intended to be a representationthat given embodiments of this technology have, or have not, been madeor tested.

All publications and patent applications mentioned in this specificationare herein incorporated by reference in their entirety to the sameextent as if each individual publication or patent application wasspecifically and individually indicated to be incorporated by reference,especially referenced is disclosure appearing in the same sentence,paragraph, page or section of the specification in which theincorporation by reference appears.

The citation of references herein does not constitute an admission thatthose references are prior art or have any relevance to thepatentability of the technology disclosed herein. Any discussion of thecontent of references cited is intended merely to provide a generalsummary of assertions made by the authors of the references, and doesnot constitute an admission as to the accuracy of the content of suchreferences.

The invention claimed is:
 1. A method for removing an object bound to atooth or teeth via a dental cement or dental resin, comprising:contacting the dental cement or dental resin with a gel comprisingeugenol for a time sufficient to reduce Vickers hardness of the dentalcement or dental resin or for a time sufficient to decrease debondingforce needed to remove a metal bracket, dental appliance or dentalprosthetic from the tooth or teeth, and removing the metal bracket,dental appliance or dental prosthetic from the tooth or teeth.
 2. Themethod of claim 1, wherein the dental adhesive or cement bonds anorthodontic bracket, fixed orthodontic appliance, dental fixedappliance, or dental prosthetic to a surface of a tooth or teeth.
 3. Themethod of claim 1, wherein the gel containing eugenol comprises eugenol,at least one surfactant, and at least one gelling agent.
 4. The methodof claim 1, wherein the eugenol in the form of a gel is contained in atray that fits around parts of the tooth or teeth bonded to the metalbracket, dental appliance or dental prosthetic and that contacts theeugenol in the form of a gel with the dental cement or dental resin. 5.The method of claim 1, wherein the gel containing eugenol is contactedwith the dental cement or dental resin for at least 10 min or until thedental cement or dental resin has a Vickers hardness of no more than 70.6. The method of claim 1, wherein the gel containing eugenol iscontacted with the dental cement or dental resin for at least 24 hr. 7.The method of claim 1, further comprising brushing, buffing, polishing,washing or etching the dental cement or dental resin to remove microbialor chemical coatings prior to contacting it with the gel containingeugenol.
 8. A method for debonding metal brackets, a dental appliance ordental prosthetic comprising: filling a tray with a compositioncomprising eugenol, fitting the tray over teeth that are bonded to metalbrackets, a dental appliance, or a dental prosthetic for a timesufficient to reduce Vickers hardness of a dental cement or resinbinding the metal brackets, dental appliance or dental prosthetic to theteeth, and debonding the metal brackets, a dental appliance, or a dentalprosthetic from the teeth.